Structures and Functions of Membrane Antenna Proteins with High Resolution Solution and Solid State NMR

本研究的主要目的是建立一种结合固体核磁共振的高分辨溶液核磁共振方法来阐明膜蛋白和色素复合体的结构和功能。作为研究的对象，我们选择了细菌膜天线中的一种，即绿小体天线。这种膜天线称为LH1(采光复合体1)或B870，其活性基团由两个(α和β)多肽和两个细菌叶绿素分子组成的亚基(B820)组成。我们已经建立了利用选择性同位素浓缩的样品来阐明修复基团周围结构的方法。因此，我们用富含同位素的BCh1a和正常的亚基，或富含同位素的a和天然的β亚基和天然的Bchla亚基重组了LH1的B820亚基，并通过溶液核磁共振对这些样品进行了结构解析。在这种情况下，富含β&lt；13&gt；C的色素细叶绿素和富含~2H的蛋白质可以聚焦细菌叶绿素和环境的信号。此外，我们还对这些样品进行了多维核磁共振的广泛应用。这些研究揭示了从核磁共振的角度阐明膜蛋白的方法。LH1的整个单元，即B870太大，不能用溶液核磁共振来研究，我们试图充分利用固体高分辨核磁共振来观察核磁共振。根据溶液核磁共振知识对获得的数据进行了分析。指定的信号告诉我们，B870将由在溶液状态下具有相似结构的亚基组成。多维溶液核磁共振和同位素富集法为确定氯仿/甲醇溶液中a组分和R组分多肽的结构提供了方法

Main object of the research is to establish the method to elucidate structures and functions of membrane proteins and pigment complexes in terms of high resolution solution nuclear magnetic resonance in conjunction with solid state NMR. For the target of the studies we have selected one of the bacterial membrane antenna, and chlorosome anntena. The membrane antenna called LH1 (light harvesting complex 1) or B870 has subunits (B820) composed of two (α and β) polypeptides and two bacteriochlorophyll molecultes in the active site as the prothetic groups. We have established the methods to elucidate the structures around the prothetic group with use of selectively isotope enriched samples. Thus, we reconstituted the subunit B820 of the LH1 with the isotope enrichied BCh1 a and the normal subumits, or the isotope enriched a and the natural β subunit and the natural BChl a and could resolve the structures with use these samples by the solution NMR. In this case the ^<13>C enriched pigment bacteriochlorophylls and the ^2H enriched proteins could focus the signal of the bacteriochlorophylls and the environment. Futhermore we have make extensive use of multidimensional NMR with these samples. These studies have disclosed the method to elucidate membrane proteins in terms of NMR. The whole unit of LH1, i.e., B870 is too large to be investigated by the solution NMR, we have tried to observe the NMR in full use of solid high resolution NMR. The obtained data have been analyzed in terms of the knowledge of the solution NMR. The assigned signal tells us the B870 would be composed of the subunits with similar structures in the solution states. The multi-dimensional solution NMR and the isotope enrichment have afforded the method to clarify the structure of the component a and R polypeptide in the chloroform/methanol solution